1. Field
The present disclosure relates to a separation membrane and a water treatment device including the separation membrane.
2. Description of the Related Art
In order to acquire fresh water or gray water from sea water, sewage, and waste water, floating or dissolved components should be removed in conformity with the standards for drinking water. At present, reverse osmosis is widely used as a water treatment method for desalinating or making gray water out of sea water or sewage and waste water.
According to the water treatment method using a reverse osmotic membrane, a pressure corresponding to an osmotic pressure caused by the dissolved component is applied to the raw water to separate a dissolved component, such as a base (NaCl), from water. For example, the concentration of the base dissolved in sea water ranges from about 30,000 to about 45,000 ppm and the osmotic pressure caused by the concentration ranges from about 20 to about 30 atm, and a pressure of about 20 to 30 atm or higher is applied to the raw water to produce fresh water from the raw water. Typically, energy of about 6 to about 10 kW is required to produce about 1 m3 of fresh water from sea water.
Recently, an energy recollection device has been developed and applied to save energy consumed for a reverse osmosis process, but in this case, about 3 kW or more of energy is required to drive a motor of a high-pressure pump to produce about 1 m3 of fresh water from sea water.
In order to resolve the problem, a water treatment process based on forward osmosis has recently been suggested as an alternative. The forward osmosis process is economical compared with the reverse osmosis process, because the forward osmosis process does not require pressure but uses a natural osmosis phenomenon. Therefore, researchers are actively studying development of the forward osmosis process.